PaDELPy: A Python wrapper for PaDEL-Descriptor software

PaDELPy provides a Python wrapper for the PaDEL-Descriptor molecular descriptor calculation software. It exposes the PaDEL-Descriptor command-line interface to Python for computing descriptors and fingerprints from SMILES, MDL MolFiles, and SDF files.

Documentation: https://padelpy.readthedocs.io/

Installation

Install from PyPI:

pip install padelpy

Or from a clone of this repository:

git clone https://github.com/ecrl/padelpy
cd padelpy
pip install .

Requirements

• Python 3.10+ (see package classifiers)
• A system Java JRE 8+ on PATH (java -version should succeed). Continuous integration uses Eclipse Temurin 17.

PaDEL-Descriptor is bundled with PaDELPy, so a separate PaDEL download is not required. The project has no default Python dependencies beyond the standard library. Wheels are large (approximately 20+ MB) because they include the vendored PaDEL JAR and libraries.

Related projects

PaDELPy is a thin wrapper around the PaDEL-Descriptor Java engine. Other tools compute related molecular features with different engines or APIs:

• Mordred — RDKit-based descriptor calculator (different engine and dependency stack)
• RDKit descriptors and fingerprints — core cheminformatics toolkit (different descriptor set)
• padelpy2 — alternate PaDEL wrapper with an RDKit/pandas-oriented API (not drop-in compatible)

Basic usage

PaDELPy provides helpers for SMILES, MDL MolFile, and SDF inputs, plus a lower-level padeldescriptor wrapper for direct CLI control.

SMILES to descriptors / fingerprints

from_smiles accepts a SMILES string or a list of SMILES strings. A single input returns a mapping of descriptor or fingerprint names to values; a list returns a list of such mappings.

from padelpy import from_smiles

# molecular descriptors for propane
descriptors = from_smiles("CCC")

# propane and butane
descriptors = from_smiles(["CCC", "CCCC"])

# descriptors plus PubChem fingerprints
desc_fp = from_smiles("CCC", fingerprints=True)

# fingerprints only
fingerprints = from_smiles("CCC", fingerprints=True, descriptors=False)

# one worker thread
descriptors = from_smiles(["CCC", "CCCC"], threads=1)

# also write a CSV
_ = from_smiles("CCC", output_csv="descriptors.csv")

MDL MolFile to descriptors / fingerprints

from_mdl accepts a path to an MDL MolFile and returns a list of mappings, one per molecule in file order.

from padelpy import from_mdl

descriptors = from_mdl("mols.mdl")
desc_fp = from_mdl("mols.mdl", fingerprints=True)
fingerprints = from_mdl("mols.mdl", fingerprints=True, descriptors=False)
desc_fp = from_mdl("mols.mdl", threads=1)
_ = from_mdl("mols.mdl", output_csv="descriptors.csv")

SDF to descriptors / fingerprints

from_sdf accepts a path to an SDF file and returns a list of mappings, one per molecule in file order.

from padelpy import from_sdf

descriptors = from_sdf("mols.sdf")
desc_fp = from_sdf("mols.sdf", fingerprints=True)
fingerprints = from_sdf("mols.sdf", fingerprints=True, descriptors=False)
desc_fp = from_sdf("mols.sdf", threads=1)
_ = from_sdf("mols.sdf", output_csv="descriptors.csv")

Command-line wrapper

padeldescriptor forwards keyword arguments to the PaDEL-Descriptor CLI. Any combination of supported flags may be supplied.

from padelpy import padeldescriptor

padeldescriptor(config="path/to/config")
padeldescriptor(mol_dir="molecules.mdl", d_file="descriptors.csv")
padeldescriptor(mol_dir="molecules.sdf", d_file="descriptors.csv")
padeldescriptor(mol_dir="molecules.smi", d_file="descriptors.csv")
padeldescriptor(mol_dir="path/to/mols/", d_file="descriptors.csv")

padeldescriptor(
    mol_dir="molecules.smi",
    d_file="descriptors.csv",
    d_2d=True,
    d_3d=True,
    fingerprints=True,
    convert3d=True,
    descriptortypes="path/to/descriptortypes",
    detectaromaticity=True,
    log=True,
    removesalt=True,
    retain3d=True,
    retainorder=True,
    standardizenitro=True,
    standardizetautomers=True,
    tautomerlist="path/to/tautomers",
    usefilenameasmolname=True,
    maxcpdperfile=32,
    maxruntime=10000,
    waitingjobs=10,
    threads=2,
    headless=True,
)

Contributing, reporting issues, and support

To contribute, open a pull request. New features should include tests and clear documentation.

To report bugs or request features, file a GitHub issue. Include error messages, operating system, Java version (java -version), and Python version when reporting problems.

For additional questions, contact Travis Kessler (travis.j.kessler@gmail.com).